When construction of the World Trade Center’s North and South towers was completed in 1973, the Pulitzer Prize–winning architecture critic Ada Louise Huxtable wrote in the New York Times that the world’s tallest towers ”are big buildings, but they are not great architecture…The Port Authority [the WTC government developer] has built the ultimate Disneyland fairy-tale blockbuster. It is General Motors Gothic.” It was not a glowing review, and the “Twin Towers,” as they would come to be known in New York City and beyond, were hardly hometown darlings. A 1987 New York magazine cover story, “The Buildings New Yorkers Love to Hate,” in which the towers came in fifth in a list of 10, summed it up: “For all the hoopla surrounding them and the 130,000 people who pass through daily, they seem the Scylla and Charybdis of lower Manhattan.”

Despite the tepid reception, the towers quickly became the symbol for New York. Soon photographers, inspired by their simple design and powerful rise from the southern tip of Manhattan island, found that dramatic images of the city could be made from the ground, the air, and the water. From above, the towers were the center of a five-point star that make up the boroughs of New York City. They were impossible to ignore, and residents eventually embraced them as integral to the city, a close third behind the beloved Empire State and Chrysler buildings.

Now in the post-9/11 city, the Twin Towers are both symbol and icon. They are seen everywhere here if you look. They are drawn in the logos of local shops and restaurants, still a subtle part of the skyline, like a phantom limb. Ahead of the 20th anniversary of the fall of the towers, Fortune has teamed with photographer Mark Peterson to explore how, two decades later, the towers still shape the city where they once stood.